A new indolizidine synthesis based upon acyl alkoxycyclopropane chemistry provided all four diastereoisomers of the frog skin alkaloid, GTX-223AB. Samples of three of these diastereomers provided by groups under Hart (Ohio State) and Macdonald (Vanderbilt) permitted the assignment of structures to allfour diastereomers. The synthetic hydrogenation mixture and coinjections with the natural frog-skin alkaloid led to the assignment of the 5E,9E configuration to it and confirmed the 3-butyl-5- propylindolizidine structure proposed by Daly and co-workers in 1978. Side-chain hydroxylated congeners are likely to have the same 5#,9E configuration.